JPWO2017130889A1 - Latex composition - Google Patents

Abstract

  Provided is a latex composition obtained by adding an aqueous aluminum compound solution to a latex of a carboxyl group-containing synthetic polyisoprene and / or a carboxyl group-containing styrene-isoprene-styrene block copolymer. In the latex composition of the present invention, the aluminum compound aqueous solution preferably has a pH of 5 to 13. In the latex composition of the present invention, the aqueous aluminum compound solution is preferably an aqueous solution of a metal salt of aluminate.

Description

  The present invention relates to a latex composition, and more specifically, a dip-molded product having excellent mechanical properties and capable of preventing the occurrence of allergic symptoms of delayed type allergy (Type IV) in addition to immediate type allergy (Type I). The present invention relates to a latex composition capable of providing a film molded body such as.

  Conventionally, a film molded body obtained by molding a latex composition containing latex of natural rubber into a film shape is known. For example, as a film molded body, a dip molded body obtained by dip molding a latex composition containing natural rubber latex and used in contact with a human body such as a nipple, a balloon, a glove, a balloon, and a sac is known. It has been. However, since latex of natural rubber contains a protein that causes symptoms of immediate allergy (Type I) in the human body, there are cases where there is a problem as a dip-molded body that is in direct contact with living mucous membranes or organs. Therefore, studies have been made on using synthetic polyisoprene or styrene-isoprene-styrene block copolymer latex instead of natural rubber latex (Patent Document 1).

  However, in the technique using the latex of such synthetic polyisoprene or styrene-isoprene-styrene block copolymer, it is possible to prevent the occurrence of immediate allergy (Type I), while in the manufacturing process of the dip-molded product, If the amount of the vulcanization accelerator and sulfur vulcanization accelerator used is too large, the resulting dip-molded product will cause delayed allergy (Type) due to sulfur contained in the dip-molded product when touched by the human body. IV) allergic symptoms may occur.

International Publication No. 2014/129547

  The present invention has been made in view of such a situation, has excellent mechanical properties, and can prevent the occurrence of allergic symptoms of delayed type allergy (Type IV) in addition to immediate type allergy (Type I). It is an object of the present invention to provide a latex composition capable of providing a dip-molded article, and a film molded body such as a dip-molded body obtained by using such a latex composition.

  As a result of intensive studies to achieve the above object, the present inventors have added an aqueous aluminum compound solution to the latex of a carboxyl group-containing synthetic polyisoprene and / or a carboxyl group-containing styrene-isoprene-styrene block copolymer. It has been found that the above object can be achieved by the latex composition, and the present invention has been completed.

  That is, according to the present invention, there is provided a latex composition obtained by adding an aqueous aluminum compound solution to a latex of carboxyl group-containing synthetic polyisoprene and / or carboxyl group-containing styrene-isoprene-styrene block copolymer.

In the latex composition of the present invention, the aluminum compound aqueous solution preferably has a pH of 5 to 13.
In the latex composition of the present invention, the aqueous aluminum compound solution is preferably an aqueous solution of a metal salt of aluminate.
In the latex composition of the present invention, the carboxyl group-containing synthetic polyisoprene is preferably obtained by graft polymerization of a monomer having a carboxyl group to the synthetic polyisoprene.
In the latex composition of the present invention, the carboxyl group-containing styrene-isoprene-styrene block copolymer is obtained by graft polymerization of a monomer having a carboxyl group to the styrene-isoprene-styrene block copolymer. Preferably there is.
The latex composition of the present invention comprises 0.05 to 1.0 parts by weight of sulfur based on a total of 100 parts by weight of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing styrene-isoprene-styrene block copolymer. It is preferable to further contain a vulcanizing agent.
The latex composition of the present invention comprises 0.05 to 1.0 parts by weight of sulfur based on a total of 100 parts by weight of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing styrene-isoprene-styrene block copolymer. It is preferable to further contain a vulcanization accelerator.
The latex composition of the present invention preferably has a pH of 7-13.

Moreover, according to this invention, the film molded object which consists of a latex composition of the said invention is provided.
Moreover, according to this invention, the manufacturing method of a dip molded object provided with the process of dip-molding the latex composition of the said invention is provided.

  INDUSTRIAL APPLICABILITY According to the present invention, a latex composition that is excellent in mechanical properties and can provide a dip-molded product that can prevent the occurrence of allergic symptoms of delayed type allergy (Type IV) in addition to immediate type allergy (Type I). And a film molded article such as a dip molded article obtained by using such a latex composition and having the above characteristics.

  In the latex composition of the present invention, an aqueous solution of an aluminum compound is added to a latex of a carboxyl group-containing synthetic polyisoprene and / or a carboxyl group-containing styrene-isoprene-styrene block copolymer (hereinafter sometimes abbreviated as “SIS”). Add it.

Carboxyl group-containing synthetic polyisoprene latex The carboxyl group-containing synthetic polyisoprene latex used in the present invention is a latex of a polymer obtained by introducing a carboxyl group into a synthetic polyisoprene obtained by polymerizing a monomer containing isoprene. It is. In the following, first, the synthetic polyisoprene used for producing the carboxyl group-containing synthetic polyisoprene latex used in the present invention will be described.

  The synthetic polyisoprene may be a homopolymer of isoprene or a copolymer of other ethylenically unsaturated monomers copolymerizable with isoprene. The content of the isoprene unit in the synthetic polyisoprene is flexible and it is easy to obtain a dip-molded article excellent in tensile strength. Therefore, it is preferably 70% by weight or more, more preferably 90% by weight, based on all monomer units. More preferably, it is 95% by weight or more, particularly preferably 100% by weight (isoprene homopolymer).

  Examples of other ethylenically unsaturated monomers copolymerizable with isoprene include conjugated diene monomers other than isoprene such as butadiene, chloroprene and 1,3-pentadiene; acrylonitrile, methacrylonitrile, fumaronitrile, α- Ethylenically unsaturated nitrile monomers such as chloroacrylonitrile; vinyl aromatic monomers such as styrene and alkylstyrene; methyl (meth) acrylate (meaning “methyl acrylate and / or methyl methacrylate”; The same applies to ethyl (meth) acrylate, etc.), ethylenically unsaturated carboxylic acid ester monomers such as ethyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid-2-ethylhexyl; Is mentioned. These other ethylenically unsaturated monomers copolymerizable with isoprene may be used singly or in combination.

Synthetic polyisoprene is produced in an inert polymerization solvent using a conventionally known method, for example, a Ziegler polymerization catalyst composed of trialkylaluminum-titanium tetrachloride, or an alkyllithium polymerization catalyst such as n-butyllithium or sec-butyllithium. It can be obtained by solution polymerization of isoprene and another copolymerizable ethylenically unsaturated monomer used as necessary. The polymer solution of synthetic polyisoprene obtained by solution polymerization may be used as it is for the production of synthetic polyisoprene latex described later. However, after taking out solid synthetic polyisoprene from the polymer solution, it is dissolved in an organic solvent. And it can also be used for manufacture of synthetic polyisoprene latex.
At this time, impurities such as a residue of the polymerization catalyst remaining in the polymer solution after the synthesis may be removed. Moreover, you may add the anti-aging agent mentioned later to the solution during superposition | polymerization or after superposition | polymerization. Commercially available solid synthetic polyisoprene can also be used.

  As the isoprene units in the synthetic polyisoprene, there are four types of cis bond units, trans bond units, 1,2-vinyl bond units, and 3,4-vinyl bond units depending on the bond state of isoprene. From the viewpoint of improving the tensile strength of the resulting dip-molded product, the content of cis-bond units in the isoprene units contained in the synthetic polyisoprene is preferably 70% by weight or more, more preferably 90% by weight based on the total isoprene units. % Or more, more preferably 95% by weight or more.

  The weight average molecular weight of the synthetic polyisoprene is preferably 10,000 to 5,000,000, more preferably 500,000 to 3,000,000, and even more preferably, in terms of standard polystyrene by gel permeation chromatography analysis. Is 700,000 to 2,000,000. By setting the weight average molecular weight of the synthetic polyisoprene within the above range, the tensile strength of the dip-molded product is improved and the synthetic polyisoprene latex tends to be easily manufactured.

  The polymer Mooney viscosity (ML1 + 4, 100 ° C.) of the synthetic polyisoprene is preferably 50 to 100, more preferably 60 to 95, still more preferably 70 to 90, and most preferably 75 to 85.

  And a carboxyl group containing synthetic polyisoprene can be obtained by introduce | transducing a carboxyl group into the synthetic polyisoprene manufactured in this way. The method for introducing a carboxyl group into the synthetic polyisoprene is not particularly limited, and examples thereof include a method of graft polymerization of a monomer having a carboxyl group on the synthetic polyisoprene in an aqueous phase. At this time, in order to graft-polymerize a monomer having a carboxyl group in the aqueous phase, it is desirable to use a synthetic polyisoprene latex.

  As a method for obtaining a synthetic polyisoprene latex, for example, (1) a solution or fine suspension of a synthetic polyisoprene dissolved or finely dispersed in an organic solvent is emulsified in water in the presence of an anionic surfactant. (2) Isoprene alone or a mixture of isoprene and an ethylenically unsaturated monomer copolymerizable therewith with anionic surface activity A method of directly producing a synthetic polyisoprene latex by emulsion polymerization or suspension polymerization in the presence of an agent. Synthetic polyisoprene having a high ratio of cis-bond units in isoprene units can be used. From the viewpoint of easily obtaining a dip-molded article having excellent mechanical properties such as tensile strength, the production method (1) is preferred.

  Examples of the organic solvent used in the production method (1) above include aromatic hydrocarbon solvents such as benzene, toluene and xylene; alicyclic hydrocarbon solvents such as cyclopentane, cyclopentene, cyclohexane and cyclohexene; pentane, hexane, And aliphatic hydrocarbon solvents such as heptane; halogenated hydrocarbon solvents such as methylene chloride, chloroform and ethylene dichloride; Of these, alicyclic hydrocarbon solvents are preferred, with cyclohexane being particularly preferred.

  The amount of the organic solvent used is preferably 2,000 parts by weight or less, more preferably 20 to 1,500 parts by weight, still more preferably 500 to 1000, and most preferably 100 parts by weight based on 100 parts by weight of the synthetic polyisoprene. ~ 400.

  Examples of the anionic surfactant used in the production method (1) include fatty acid salts such as sodium laurate, potassium myristate, sodium palmitate, potassium oleate, sodium linolenate, and sodium rosinate; dodecylbenzenesulfone Alkylbenzene sulfonates such as sodium acetate, potassium dodecylbenzenesulfonate, sodium decylbenzenesulfonate, potassium decylbenzenesulfonate, sodium cetylbenzenesulfonate, potassium cetylbenzenesulfonate; sodium di (2-ethylhexyl) sulfosuccinate, di (2-ethylhexyl) alkyl sulfosuccinates such as potassium sulfosuccinate and sodium dioctyl sulfosuccinate; sodium lauryl sulfate, potassium lauryl sulfate and the like Rualkyl sulfate salt; polyoxyethylene alkyl ether sulfate ester salt such as sodium polyoxyethylene lauryl ether sulfate and potassium polyoxyethylene lauryl ether sulfate; monoalkyl phosphate salt such as sodium lauryl phosphate and potassium lauryl phosphate; Can be mentioned.

  Among these anionic surfactants, fatty acid salts, alkylbenzene sulfonates, alkyl sulfosuccinates, alkyl sulfate esters and polyoxyethylene alkyl ether sulfate salts are preferable, and fatty acid salts and alkylbenzene sulfonates are particularly preferable.

Moreover, since the polymerization catalyst (especially aluminum and titanium) derived from the synthetic polyisoprene can be removed more efficiently and the generation of aggregates during production of the latex composition is suppressed, alkylbenzene. It is preferable to use at least one selected from the group consisting of sulfonates, alkylsulfosuccinates, alkylsulfate esters and polyoxyethylene alkylether sulfates in combination with fatty acid salts, alkylbenzenesulfonates and It is particularly preferable to use a fatty acid salt in combination. Here, sodium rosinate and potassium rosinate are preferable as the fatty acid salt, and sodium dodecylbenzene sulfonate and potassium dodecylbenzene sulfonate are preferable as the alkylbenzene sulfonate. These surfactants may be used alone or in combination of two or more.

  As described above, the fatty acid salt is used in combination with at least one selected from the group consisting of alkylbenzene sulfonate, alkylsulfosuccinate, alkyl sulfate ester salt and polyoxyethylene alkyl ether sulfate ester salt. Thus, the obtained latex contains at least one selected from alkylbenzene sulfonate, alkylsulfosuccinate, alkyl sulfate ester salt and polyoxyethylene alkyl ether sulfate ester salt and a fatty acid salt. .

  In the production method of (1), a surfactant other than an anionic surfactant may be used in combination, and as a surfactant other than such an anionic surfactant, α, β-inactive Examples thereof include copolymerizable surfactants such as sulfoesters of saturated carboxylic acids, sulfate esters of α, β-unsaturated carboxylic acids, and sulfoalkylaryl ethers.

  Furthermore, non-ionic such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester, etc., as long as it does not inhibit coagulation by the coagulant used for dip molding A surfactant may be used in combination.

  The amount of the anionic surfactant used in the production method (1) is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, with respect to 100 parts by weight of the synthetic polyisoprene. More preferably, it is 1-10 weight part. In addition, when using 2 or more types of surfactant, it is preferable to make these total usage into the said range. That is, for example, when at least one selected from alkyl benzene sulfonate, alkyl sulfosuccinate, alkyl sulfate ester salt and polyoxyethylene alkyl ether sulfate ester salt and fatty acid salt are used in combination, The total amount used is preferably within the above range. If the amount of the anionic surfactant used is too small, a large amount of aggregates may be generated during emulsification. Conversely, if the amount is too large, foaming tends to occur and pinholes may be generated in the resulting dip-molded product. There is.

  Also, when an anionic surfactant is used in combination with a fatty acid salt and at least one selected from alkylbenzene sulfonate, alkylsulfosuccinate, alkyl sulfate ester salt and polyoxyethylene alkyl ether sulfate ester salt The ratio of use thereof is determined by changing at least one surface activity selected from “fatty acid salts”: “alkyl benzene sulfonates, alkyl sulfosuccinates, alkyl sulfates and polyoxyethylene alkyl ether sulfates”. The weight ratio of “total agent” is preferably in the range of 1: 1 to 10: 1, and more preferably in the range of 1: 1 to 7: 1. When the usage ratio of at least one surfactant selected from alkylbenzene sulfonate, alkylsulfosuccinate, alkyl sulfate ester salt and polyoxyethylene alkyl ether sulfate ester salt is too high, when handling synthetic polyisoprene There is a possibility that foaming may become intense, and as a result, operations such as standing for a long time and addition of an antifoaming agent are required, which may lead to deterioration in workability and cost increase. On the other hand, if the use ratio of at least one surfactant selected from alkylbenzene sulfonate, alkylsulfosuccinate, alkyl sulfate ester salt and polyoxyethylene alkyl ether sulfate ester salt is too small, it has a carboxyl group. When the monomer is graft-polymerized, aggregates may be generated when the monomer having a carboxyl group is added.

  The amount of water used in the production method (1) is preferably 10 to 1,000 parts by weight, more preferably 30 to 500 parts by weight, and most preferably 100 parts by weight of the organic solvent solution of synthetic polyisoprene. Is 50-100. Examples of the water to be used include hard water, soft water, ion exchange water, distilled water, zeolite water and the like, and soft water, ion exchange water and distilled water are preferable.

  An apparatus for emulsifying a solution or fine suspension of a synthetic polyisoprene dissolved or finely dispersed in an organic solvent in water in the presence of an anionic surfactant is generally one commercially available as an emulsifier or a disperser. If it does not specifically limit, it can be used. The method of adding the anionic surfactant to the solution or fine suspension of the synthetic polyisoprene is not particularly limited, and is previously added to either the water or the synthetic polyisoprene solution or the fine suspension, or both. It may be added, or it may be added to the emulsified liquid during the emulsification operation, or it may be added all at once or dividedly.

  Examples of the emulsifier include batch type emulsification such as trade name “Homogenizer” (manufactured by IKA), trade name “Polytron” (manufactured by Kinematica), trade name “TK auto homomixer” (manufactured by Tokushu Kika Kogyo Co.) Machine: Trade name “TK Pipeline Homomixer” (made by Tokushu Kika Kogyo Co., Ltd.), trade name “Colloid Mill” (made by Shinko Pantech Co., Ltd.), trade name “Slasher” (made by Nippon Coke Industries, Ltd.), trade name “ "Trigonal wet milling machine" (Mitsui Miike Chemical Co., Ltd.), trade name "Cabitron" (Eurotech Co., Ltd.), trade name "Milder" (Pacific Kiko Co., Ltd.), trade name "Fine Flow Mill" (Pacific Kiko Co., Ltd.) Product name “Microfluidizer” (manufactured by Mizuho Kogyo Co., Ltd.), product name “Nanomizer” (manufactured by Nanomizer), product name “APV Gaurin” (Gau High-pressure emulsifiers such as “Membrane Emulsifier” (manufactured by Chilling Industries Co., Ltd.); Ultrasonic emulsifiers such as trade name “Ultrasonic Homogenizer” (manufactured by Branson); The conditions for the emulsification operation by the emulsification apparatus are not particularly limited, and the treatment temperature, treatment time, etc. may be appropriately selected so as to obtain a desired dispersion state.

In the production method (1), it is desirable to remove the organic solvent from the emulsion obtained through the emulsification operation.
As a method for removing the organic solvent from the emulsion, a method capable of setting the content of the organic solvent (preferably alicyclic hydrocarbon solvent) in the obtained synthetic polyisoprene latex to 500 ppm by weight or less is preferable. For example, methods such as vacuum distillation, atmospheric distillation, steam distillation, and centrifugation can be employed.

  Next, using the synthetic polyisoprene latex obtained by the production method of (1) above, the carboxyl group used in the present invention is graft-polymerized with a monomer having a carboxyl group on the synthetic polyisoprene in the aqueous phase. Containing synthetic polyisoprene latex can be obtained.

  The method for obtaining a carboxyl group-containing synthetic polyisoprene latex by graft polymerization of a monomer having a carboxyl group to synthetic polyisoprene in an aqueous phase is not particularly limited, and a conventionally known graft polymerization method can be employed.

Examples of the monomer having a carboxyl group include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; ethylenically unsaturated polyvalent monomers such as itaconic acid, maleic acid, fumaric acid, and butenetricarboxylic acid. Carboxylic acid monomers; partial ester monomers of ethylenically unsaturated polyvalent carboxylic acids such as monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate; polyvalent carboxylic acids such as maleic anhydride and citraconic anhydride An acid anhydride; and the like can be mentioned, but the ethylenically unsaturated monocarboxylic acid monomer is preferable, and acrylic acid and methacrylic acid are particularly preferable because the effects of the present invention become more remarkable. These monomers may be used alone or in combination of two or more.
In addition, the carboxyl group includes a salt with an alkali metal, ammonia or the like.

  The amount of the monomer having a carboxyl group is preferably 0.01 to 100 parts by weight, more preferably 0.01 to 40 parts by weight, and still more preferably 100 parts by weight of synthetic polyisoprene. 0.5 parts by weight to 20 parts by weight. When the usage-amount of the monomer which has a carboxyl group is too little, there exists a tendency for the tensile strength of the obtained dip molding to become low. Conversely, if the amount of the monomer having a carboxyl group is too large, the resulting carboxyl group-containing synthetic polyisoprene latex may have too high a viscosity and may be difficult to handle.

  The method for adding the monomer having a carboxyl group to the synthetic polyisoprene latex is not particularly limited, and known addition methods such as batch addition, divided addition, and continuous addition can be employed.

  In the present invention, the tetrahydrofuran-insoluble content of the carboxyl group-containing synthetic polyisoprene contained in the carboxyl group-containing synthetic polyisoprene latex is preferably 30% by weight or more, more preferably 60% by weight or more. In producing the carboxyl group-containing synthetic polyisoprene latex, in addition to the monomer having a carboxyl group, an organic peroxide and a reducing agent are added to the synthetic polyisoprene latex obtained by the production method of (1) above. It is preferable to add a redox catalyst combined with the above to graft-polymerize the monomer having a carboxyl group in the aqueous phase and simultaneously cause the polyisoprene to undergo a crosslinking reaction. By setting the tetrahydrofuran-insoluble content to 30% by weight or more, the tensile strength of the resulting dip-molded product can be further increased.

  Examples of the organic peroxide used for the crosslinking reaction include diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t- Examples thereof include butyl peroxide, isobutyryl peroxide, and benzoyl peroxide, and 1,1,3,3-tetramethylbutyl hydroperoxide is preferable from the viewpoint of improving the mechanical properties of the resulting dip-molded product. These organic peroxides may be used alone or in combination of two or more.

  Although the usage-amount of an organic peroxide is not specifically limited, Preferably it is 0.01-3 weight part with respect to 100 weight part of synthetic polyisoprenes, More preferably, it is 0.1-1 weight part.

  Examples of the reducing agent include compounds containing metal ions in a reduced state such as ferrous sulfate and cuprous naphthenate; sulfonic acid compounds such as sodium methanesulfonate; amine compounds such as dimethylaniline; It is done. These reducing agents may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although the usage-amount of a reducing agent is not specifically limited, It is preferable that it is 0.01-1 weight part with respect to 1 weight part of organic peroxides.

  When a synthetic polyisoprene is crosslinked simultaneously with graft polymerization of a monomer having a carboxyl group using a redox catalyst in which an organic peroxide and a reducing agent are combined, a conventionally known graft polymerization method can be employed. Moreover, the addition method of an organic peroxide and a reducing agent can also be a known addition method such as batch addition, divided addition, or continuous addition.

  The reaction temperature is preferably 5 to 70 ° C, more preferably 10 to 70 ° C when graft polymerization is performed using a redox catalyst.

  The graft polymerization of the monomer having a carboxyl group and the crosslinking of the synthetic polyisoprene may be performed separately. In this case, as a polymerization catalyst (graft polymerization catalyst) of the graft polymerization, for example, sodium persulfate Inorganic peroxides such as potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide; diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, 1,1,3,3-tetra Organic peroxides such as methylbutyl hydroperoxide, di-t-butyl peroxide, isobutyryl peroxide, benzoyl peroxide; 2,2′-azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile Azo compounds such as methyl azobisisobutyrate; Can be exemplified, from the viewpoint of improving mechanical properties of the resulting dip-molded product, an organic peroxide is preferred, 1,1,3,3-tetramethylbutyl hydroperoxide is particularly preferred.

  The above graft polymerization catalysts can be used alone or in combination of two or more. Although the usage-amount of a graft polymerization catalyst changes with kinds, Preferably it is 0.1-10 weight part with respect to 100 weight part of synthetic polyisoprenes, More preferably, it is 0.2-5 weight part. Moreover, it does not specifically limit as a method of adding a graft polymerization catalyst, Well-known addition methods, such as collective addition, divided addition, and continuous addition, are employable.

  The conversion of graft polymerization is preferably 95% by weight or more, particularly preferably 97% by weight or more. If the conversion of the graft polymerization is too low, the tensile strength and tear strength tend to be low.

  The introduction ratio of the carboxyl group-containing monomer (carboxyl group modification ratio) in the carboxyl group-containing synthetic polyisoprene thus obtained is not particularly limited, but is preferably 0.1 with respect to all isoprene units. -10 wt%, more preferably 0.5-5 wt%, still more preferably 1-3 wt%. By setting the introduction ratio of the monomer having a carboxyl group within the above range, the hardness of the dip-molded body such as a glove becomes moderate, and the mechanical stability of the carboxyl group-containing synthetic polyisoprene latex is improved. Thus, the effect of improving the tensile strength and tear strength of the resulting dip-molded product is easily obtained.

  The carboxyl group-containing synthetic polyisoprene latex obtained as described above is usually blended in the latex field, and is a pH adjuster, antifoaming agent, preservative, chelating agent, oxygen scavenger, dispersant, aging. You may mix | blend additives, such as an inhibitor.

  Examples of the pH adjuster include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal hydrogen carbonates such as sodium bicarbonate; ammonia An organic amine compound such as trimethylamine or triethanolamine; an alkali metal hydroxide or ammonia is preferred.

  Further, after the graft polymerization, if necessary, in order to increase the solid content concentration of the carboxyl group-containing synthetic polyisoprene latex, a concentration operation may be performed by a method such as vacuum distillation, atmospheric distillation, centrifugation, membrane concentration, etc. However, it is preferable to perform centrifugation from the viewpoint that the residual amount of the anionic surfactant in the carboxyl group-containing synthetic polyisoprene latex can be adjusted.

When the carboxyl group-containing synthetic polyisoprene latex after graft polymerization is subjected to a centrifuge, it is preferable to add a pH adjuster in advance to make the latex pH 7 or more in order to improve the mechanical stability of the latex, More preferably, the pH is set to 9 or more. As the pH adjuster, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide or ammonia are preferable.
When the pH of the latex is adjusted, the carboxyl group introduced by modification may be in a salt state.

  Centrifugation, for example, using a continuous centrifuge, the centrifugal force is preferably 4,000 to 5,000 G, and the solid content concentration of the carboxyl group-containing synthetic polyisoprene latex before centrifugation is preferably 2 to 15. It is preferable that the weight%, the flow rate fed to the centrifuge is preferably 500 to 2000 Kg / hr, and the back pressure (gauge pressure) of the centrifuge is preferably 0.03 to 1.6 MPa.

  The solid content concentration of the carboxyl group-containing synthetic polyisoprene latex used in the present invention is preferably 30 to 70% by weight, more preferably 50 to 70% by weight. By setting the solid content concentration within the above range, separation of the polymer particles when the latex is stored can be suppressed, and generation of coarse aggregates due to aggregation of the polymer particles can be suppressed.

  The volume average particle diameter of the carboxyl group-containing synthetic polyisoprene latex used in the present invention is preferably 0.1 to 10 μm, more preferably 0.5 to 3 μm, and still more preferably 1 to 2 μm. By setting the volume average particle diameter in the above range, the latex viscosity becomes moderate and easy to handle, and when the carboxyl group-containing synthetic polyisoprene latex is stored, the formation of a film on the latex surface can be suppressed.

  Further, the total content of the anionic surfactant in the carboxyl group-containing synthetic polyisoprene latex used in the present invention is preferably 5 parts by weight or less, more preferably 3 parts by weight with respect to 100 parts by weight of the carboxyl group-containing synthetic polyisoprene. The amount is not more than parts by weight, more preferably 0.1 to 3 parts by weight. When the total content of the anionic surfactant is in the above range, the occurrence of foaming is suppressed, and a dip-molded product having excellent tensile strength and no pinholes is easily obtained.

Carboxyl group-containing styrene-isoprene-styrene block copolymer latex The carboxyl group-containing styrene-isoprene-styrene block copolymer latex (carboxyl group-containing SIS latex) used in the present invention is a block copolymer of styrene and isoprene (SIS). (“S” represents a styrene block, and “I” represents an isoprene block.) Latex. In the latex composition of the present invention, a carboxyl group-containing SIS latex can be used in addition to the carboxyl group-containing synthetic polyisoprene latex described above or in place of the carboxyl group-containing synthetic polyisoprene latex described above.

  The carboxyl group-containing SIS latex used in the present invention is a latex of carboxyl group-containing SIS obtained by introducing a carboxyl group into SIS obtained by polymerizing a monomer containing styrene and isoprene. Although it does not specifically limit as a manufacturing method of carboxyl group containing SIS used by this invention, Like the latex of the carboxyl group containing synthetic polyisoprene mentioned above, SIS latex is obtained and the obtained SIS latex is used in the aqueous phase. Then, a method of graft polymerization of a monomer having a carboxyl group on SIS can be used.

  The production method of the SIS latex used in the present invention is not particularly limited, but a SIS solution or fine suspension dissolved or finely dispersed in an organic solvent is emulsified in water in the presence of a surfactant, and if necessary. A method of producing an SIS latex by removing the organic solvent is preferred.

SIS can be obtained by a conventionally known method, for example, block copolymerization of isoprene and styrene in an inert polymerization solvent using an active organic metal such as n-butyllithium as an initiator. The obtained SIS polymer solution may be used as it is for the production of SIS latex, but after the solid SIS is taken out from the polymer solution, the solid SIS is dissolved in an organic solvent. It can also be used for the production of latex.
At this time, impurities such as a residue of the polymerization catalyst remaining in the polymer solution after the synthesis may be removed. Moreover, you may add the anti-aging agent mentioned later to the solution during superposition | polymerization or after superposition | polymerization. Commercially available solid SIS can also be used.

As the organic solvent, the same solvents as in the case of the synthetic polyisoprene can be used, and aromatic hydrocarbon solvents and alicyclic hydrocarbon solvents are preferable, and cyclohexane and toluene are particularly preferable.
In addition, the usage-amount of an organic solvent is 50-2,000 normally with respect to 100 weight part of SIS, Preferably it is 80-1,000 weight part, More preferably, it is 10-500 weight part, More preferably, it is 150-300 weight part. It is.

  Examples of the surfactant are the same as those in the case of the synthetic polyisoprene, an anionic surfactant is preferable, and sodium rosinate and sodium dodecylbenzenesulfonate are particularly preferable.

  The amount of the surfactant used is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, and most preferably 1 to 10 parts by weight with respect to 100 parts by weight of SIS. If the amount is too small, the stability of the latex tends to be inferior. On the other hand, if the amount is too large, foaming tends to occur and problems may occur during dip molding.

The amount of water used in the SIS latex production method described above is preferably 10 to 1,000 parts by weight, more preferably 30 to 500 parts by weight, and most preferably 50 parts per 100 parts by weight of the organic solvent solution of SIS. ~ 100.
Examples of the water used include hard water, soft water, ion exchange water, distilled water, and zeolite water. Moreover, you may use together the polar solvent represented by alcohol, such as methanol, with water.

  An apparatus for emulsifying a SIS organic solvent solution or fine suspension in water in the presence of a surfactant can be exemplified by the same one as in the case of the synthetic polyisoprene. The addition method of the surfactant is not particularly limited, and it may be added in advance to either water or SIS organic solvent solution or fine suspension, or both, or during the emulsification operation. In addition, it may be added to the emulsion, or may be added all at once or in divided portions.

  In the SIS latex production method described above, it is preferable to obtain the SIS latex by removing the organic solvent from the emulsion obtained through the emulsification operation. The method for removing the organic solvent from the emulsion is not particularly limited, and methods such as vacuum distillation, atmospheric distillation, steam distillation, and centrifugation can be employed.

  In addition, after removing the organic solvent, if necessary, in order to increase the solid content concentration of the SIS latex, a concentration operation may be performed by a method such as vacuum distillation, atmospheric distillation, centrifugation, membrane concentration or the like.

  The solid content concentration of the SIS latex used in the present invention is preferably 30 to 70% by weight, more preferably 50 to 70% by weight. If the solid content concentration is too low, there is a concern that the latex particles (SIS particles) in the SIS latex may be separated when the SIS latex is stored. Conversely, if the SIS latex is too high, the SIS particles are aggregated to form coarse aggregates. May occur.

  In addition, SIS latex contains additives such as pH adjusters, antifoaming agents, preservatives, cross-linking agents, chelating agents, oxygen scavengers, dispersants, and anti-aging agents that are usually added in the latex field. You may do it. Examples of the pH adjuster include the same ones as in the case of the synthetic polyisoprene, and alkali metal hydroxides or ammonia are preferable.

The content of styrene units in the styrene block in the SIS contained in the SIS latex thus obtained is preferably 70 to 100% by weight, more preferably 90 to 100% by weight, based on all monomer units. More preferably, it is 100% by weight.
Further, the content of isoprene units in the isoprene block in the SIS is preferably 70 to 100% by weight, more preferably 90 to 100% by weight, and still more preferably 100% by weight with respect to all monomer units.
In addition, the content ratio of the styrene unit and the isoprene unit in the SIS is usually 1:99 to 90:10, preferably 3:97 to 70:30, more preferably 5 in a weight ratio of “styrene unit: isoprene unit”. : 95 to 50:50, and more preferably 10:90 to 30:70.

The weight average molecular weight of SIS is preferably 10,000 to 1,000,000, more preferably 50,000 to 5,000,000, and still more preferably 100, in terms of standard polystyrene by gel permeation chromatography analysis. , 3,000 to 3,000,000. By setting the weight average molecular weight of SIS within the above range, the balance between the tensile strength and flexibility of the dip-formed product is improved, and the latex of SIS tends to be easily produced.

  The volume average particle diameter of latex particles (SIS particles) in the SIS latex is preferably 0.1 to 10 μm, more preferably 0.5 to 3 μm, and still more preferably 1 to 2 μm. By setting the volume average particle diameter of the latex particles in the above range, the latex viscosity becomes moderate and easy to handle, and when the SIS latex is stored, the formation of a film on the latex surface can be suppressed.

  Next, the carboxyl group-containing SIS used in the present invention can be obtained by graft polymerization of a monomer having a carboxyl group in the SIS in the aqueous phase using the SIS latex obtained by the above method. As a method for graft polymerization of a monomer having a carboxyl group to SIS, for example, the same method as in the case of the above-described synthetic polyisoprene containing a carboxyl group can be used.

  Also in this case, the carboxyl group-containing SIS is contained so that the tetrahydrofuran-insoluble content of the carboxyl group-containing SIS contained in the carboxyl group-containing SIS latex is preferably 30% by weight or more, more preferably 60% by weight or more. In producing the latex, in addition to the carboxyl group-containing monomer, the SIS latex obtained by the above method is added with a redox catalyst that combines an organic peroxide and a reducing agent, It is preferable that the monomer having a carboxyl group is graft-polymerized and the SIS is crosslinked at the same time.

  The introduction ratio (carboxyl group modification ratio) of the monomer having a carboxyl group in the carboxyl group-containing SIS used in the present invention is not particularly limited, but is preferably 0.1 with respect to all isoprene units contained in the SIS. -10 wt%, more preferably 0.5-6 wt%. By setting the introduction ratio of the monomer having a carboxyl group within the above range, the hardness of the dip-molded body such as a glove becomes appropriate, and the mechanical stability of the latex of the carboxyl group-containing SIS is improved. The effect of improving the tensile strength and tear strength of the resulting dip-molded product is easily obtained.

Latex Composition The latex composition of the present invention comprises an aqueous solution of an aluminum compound in addition to the carboxyl group-containing synthetic polyisoprene and / or the carboxyl group-containing SIS latex.

  In the latex composition of the present invention, the aluminum compound acts as a crosslinking agent for crosslinking the carboxyl group-containing synthetic polyisoprene and / or the carboxyl group-containing SIS, so that it is flexible and has excellent mechanical properties such as tensile strength. A molded body is obtained. In addition, since the obtained dip-molded product has a reduced sulfur content, allergic symptoms of delayed type allergy (Type IV) in addition to immediate type allergy (Type I) were effectively prevented. It will be a thing.

  The aluminum compound aqueous solution used in the present invention is preferably one in which the aluminum compound is dissolved in water, but may be one in which a part or all of the aluminum compound is dispersed in water. The aluminum compound is not particularly limited, but aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum metal, aluminum ammonium sulfate, aluminum bromide, aluminum fluoride, aluminum sulfate / potassium, aluminum / isopropoxide, sodium aluminate, aluminum Examples include potassium acid and sodium aluminum sulfite. Among these, from the viewpoint that the carboxyl group-containing synthetic polyisoprene and / or the carboxyl group-containing SIS can be satisfactorily crosslinked, a metal salt of aluminate is preferable, and sodium aluminate is more preferable.

  The compounding amount of the aluminum compound in the latex composition of the present invention is preferably 0.1 to 10 parts by weight in terms of solid content with respect to a total of 100 parts by weight of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing SIS, More preferably, it is 0.5 to 5 parts by weight.

  Although the density | concentration of the aluminum compound in an aluminum compound aqueous solution is not specifically limited, Preferably it is 0.1 to 10 weight%, More preferably, it is 0.5 to 5 weight%.

  Moreover, the pH of the aluminum compound aqueous solution is preferably 5 to 13, more preferably 7 to 12, and still more preferably 10 to 12. By adjusting the pH to the above range, the coordination structure of the aluminum compound in the aluminum compound aqueous solution can be made suitable for acting as a cross-linking agent, and thereby the mechanical properties of the resulting dip-formed product Can be raised more appropriately. In addition, pH of aluminum compound aqueous solution can be adjusted using alkaline compounds, such as acidic compounds, such as glycolic acid, and ammonia, sodium hydroxide, potassium hydroxide, for example.

  In addition, the latex composition of the present invention has a range that does not inhibit the action and effect of the present invention (for example, a range in which the obtained dip-molded product does not cause allergic symptoms of delayed type allergy (Type IV) in the human body), You may mix | blend a sulfur type vulcanizing agent, a sulfur type vulcanization accelerator, etc. By blending a sulfur-based vulcanizing agent and a sulfur-based vulcanization accelerator, the mechanical properties of the resulting dip-molded product can be further improved.

  Examples of the sulfur vulcanizing agent include sulfur such as powdered sulfur, sulfur white, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, etc .; sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, N, N Examples thereof include sulfur-containing compounds such as' -dithio-bis (hexahydro-2H-azepinone-2), phosphorus-containing polysulfides, polymer polysulfides, and 2- (4'-morpholinodithio) benzothiazole. Of these, sulfur is preferably used. These sulfur vulcanizing agents can be used singly or in combination of two or more.

  The amount of sulfur-based vulcanizing agent used is not particularly limited as long as it does not impair the effects of the present invention, but is preferably based on a total of 100 parts by weight of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing SIS. Is 1.0 part by weight or less, more preferably 0.05 to 1.0 part by weight, still more preferably 0.05 to 0.8 part by weight, and most preferably 0.1 to 0.4 part by weight.

  As the sulfur vulcanization accelerator, those usually used in dip molding can be used. For example, diethyldithiocarbamic acid, dibutyldithiocarbamic acid, di-2-ethylhexyldithiocarbamic acid, dicyclohexyldithiocarbamic acid, diphenyldithiocarbamic acid, dibenzyldithiocarbamic acid Dithiocarbamic acids and their zinc salts; 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc, 2-mercaptothiazoline, dibenzothiazyl disulfide, 2- (2,4-dinitrophenylthio) benzothiazole, 2- (N, N-diethylthio-carbylthio) benzothiazole, 2- (2,6-dimethyl-4-morpholinothio) benzothiazole, 2- (4'-morpholino-dithio) ben Examples include thiazole, 4-morpholinyl-2-benzothiazyl disulfide, 1,3-bis (2-benzothiazyl mercaptomethyl) urea, zinc diethyldithiocarbamate, 2-mercaptobenzothiazole, and 2-mercaptobenzothiazole zinc. preferable. These vulcanization accelerators can be used alone or in combination of two or more.

  The amount of sulfur-based vulcanization accelerator used is not particularly limited as long as it does not impair the effects of the present invention, but with respect to a total of 100 parts by weight of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing SIS, Preferably it is 1.0 weight part or less, More preferably, it is 0.05-1.0 weight part, More preferably, it is 0.01-0.5 weight part, Most preferably, it is 0.05-0.25 weight part.

  Moreover, it is preferable that the latex composition of this invention contains a zinc oxide further. The content of zinc oxide is not particularly limited, but is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 2 parts by weight with respect to 100 parts by weight of the total of synthetic polyisoprene and SIS. If the amount is too small, the tensile strength of the dip-molded product tends to decrease. If the amount is too large, the stability of the carboxyl group-containing synthetic polyisoprene particles and carboxyl group-containing SIS particles in the latex composition decreases, resulting in coarseness. Aggregates may occur.

  The latex composition of the present invention further comprises a compounding agent such as a dispersant; an anti-aging agent; a reinforcing agent such as carbon black, silica, and talc; a filler such as calcium carbonate and clay; an ultraviolet absorber; a plasticizer; It can mix | blend as needed.

  Anti-aging agents include 2,6-di-4-methylphenol, 2,6-di-t-butylphenol, butylhydroxyanisole, 2,6-di-t-butyl-α-dimethylamino-p-cresol, Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, styrenated phenol, 2,2′-methylene-bis (6-α-methyl-benzyl-p-cresol), 4, Butylation of 4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylene-bis (4-methyl-6-t-butylphenol), alkylated bisphenol, p-cresol and dicyclopentadiene Phenol-based antioxidants containing no sulfur atom, such as reaction products; 2,2′-thiobis- (4-methyl-6-tert-butylphenol) ), 4,4′-thiobis- (6-tert-butyl-o-cresol), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5- Thiobisphenol-based antioxidants such as triazin-2-ylamino) phenol; phosphite-based antioxidants such as tris (nonylphenyl) phosphite, diphenylisodecyl phosphite, tetraphenyldipropylene glycol diphosphite; thiodipropion Sulfur-based antioxidants such as dilauryl acid; phenyl-α-naphthylamine, phenyl-β-naphthylamine, p- (p-toluenesulfonylamide) -diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, N, N-diphenyl-p-phenylenediamine, N-isopropyl-N′- Amine-based antioxidants such as phenyl-p-phenylenediamine and butyraldehyde-aniline condensates; quinoline antioxidants such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; -Hydroquinone anti-aging agents such as di- (t-amyl) hydroquinone; These anti-aging agents can be used alone or in combination of two or more.

  The amount of the anti-aging agent is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the total of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing SIS. .

  The method for preparing the latex composition of the present invention is not particularly limited. For example, using a dispersing machine such as a ball mill, a kneader, or a disper, an aluminum compound is added to the carboxyl group-containing synthetic polyisoprene latex and / or the carboxyl group-containing SIS latex. A method of mixing an aqueous solution and various compounding agents blended as necessary, or using the above-mentioned disperser in advance, of a desired compounding component other than a carboxyl group-containing synthetic polyisoprene latex and / or a carboxyl group-containing SIS latex Examples thereof include a method of preparing an aqueous dispersion and then mixing the aqueous dispersion with a carboxyl group-containing synthetic polyisoprene latex and / or a carboxyl group-containing SIS latex.

  The latex composition of the present invention preferably has a pH of 7 or more, more preferably in the range of 7 to 13, and still more preferably in the range of 8 to 12. Moreover, it is preferable that the solid content concentration of a latex composition exists in the range of 15 to 65 weight%.

The latex composition of the present invention is preferably aged (pre-crosslinked) before being subjected to dip molding from the viewpoint of further improving the mechanical properties of the resulting dip molded article. The time for precrosslinking is not particularly limited and depends on the temperature for precrosslinking, but is preferably 1 to 14 days, and more preferably 1 to 7 days. The pre-crosslinking temperature is preferably 20 to 40 ° C.
And after pre-crosslinking, it is preferable to store at a temperature of 10 to 30 ° C. until it is used for dip molding. When stored at a high temperature, the tensile strength of the resulting dip-molded product may decrease.

Film molded body The film molded body of the present invention is a film-shaped molded body made of the latex composition of the present invention. The film thickness of the film molded body of the present invention is preferably 0.03 to 0.50 mm, more preferably 0.05 to 0.40 mm, and particularly preferably 0.08 to 0.30 mm.

  Although it does not specifically limit as a film molded object of this invention, It is suitable that it is a dip molded object obtained by dip-molding the latex composition of this invention.

Dip Molded Body The dip molded body of the present invention is obtained by dip molding the latex composition of the present invention. Dip molding is a method in which a mold is immersed in a latex composition, the composition is deposited on the surface of the mold, the mold is then lifted from the composition, and then the composition deposited on the mold surface is dried. is there. The mold before being immersed in the latex composition may be preheated. Further, a coagulant can be used as necessary before the mold is immersed in the latex composition or after the mold is pulled up from the latex composition.

  Specific examples of the method of using the coagulant include a method in which the mold before dipping in the latex composition is immersed in a solution of the coagulant to attach the coagulant to the mold (anode coagulation dipping method), and the latex composition is deposited. There is a method of immersing the formed mold in a coagulant solution (Teag adhesion dipping method), etc., but the anode adhesion dipping method is preferable in that a dip-formed product with little thickness unevenness can be obtained.

  Specific examples of coagulants include metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetic acid such as barium acetate, calcium acetate, and zinc acetate. Salts; water-soluble polyvalent metal salts such as calcium sulfate, magnesium sulfate, and sulfates such as aluminum sulfate; Of these, calcium salts are preferable, and calcium nitrate is more preferable. These water-soluble polyvalent metal salts can be used alone or in combination of two or more.

  The coagulant is preferably used in the form of an aqueous solution. This aqueous solution may further contain a water-soluble organic solvent such as methanol or ethanol, or a nonionic surfactant. The concentration of the coagulant varies depending on the type of the water-soluble polyvalent metal salt, but is preferably 5 to 50% by weight, more preferably 10 to 30% by weight.

  After the mold is pulled up from the latex composition, the deposit formed on the mold is usually dried by heating. What is necessary is just to select drying conditions suitably.

It is then heated to crosslink the deposit formed on the mold.
The heating conditions at the time of crosslinking are not particularly limited, but are preferably 60 to 150 ° C., more preferably 100 to 130 ° C., and preferably 10 to 120 minutes.
The heating method is not particularly limited, and there are a method of heating with warm air in an oven, a method of heating by irradiating infrared rays, and the like.

  Alternatively, the mold may be washed with water or warm water to remove water-soluble impurities (for example, excess surfactant or coagulant) before or after heating the mold on which the latex composition is deposited. preferable. The warm water used is preferably 40 ° C to 80 ° C, more preferably 50 ° C to 70 ° C.

  The dip-formed body after crosslinking is detached from the mold. Specific examples of the desorption method include a method of peeling from a mold by hand, a method of peeling by water pressure or compressed air pressure, and the like. If the dip-formed product in the middle of crosslinking has sufficient strength against desorption, it may be desorbed in the middle of crosslinking, and then the subsequent crosslinking may be continued.

  The dip-molded product of the present invention is excellent in mechanical properties such as tensile strength, and can prevent the occurrence of allergic symptoms of delayed type allergy (Type IV) in addition to immediate type allergy (Type I). Therefore, it can be particularly suitably used as a glove. When the dip-molded body is a glove, in order to prevent the dip-molded bodies from sticking to each other at the contact surface, and to improve the slippage when attaching and detaching, the glove is made of inorganic fine particles such as talc and calcium carbonate or organic fine particles such as starch particles. It may be dispersed on the surface, an elastomer layer containing fine particles may be formed on the surface of the glove, or the surface layer of the glove may be chlorinated.

  In addition to the above gloves, the dip-molded body of the present invention is a medical article such as a nipple for baby bottles, a dropper, a tube, a water pillow, a balloon sac, a catheter, and a condom; a toy such as a balloon, a doll, and a ball; It can also be used for industrial articles such as molding bags and gas storage bags;

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following, “part” is based on weight unless otherwise specified. Tests or evaluation methods for physical properties and characteristics are as follows.

A tetrahydrofuran-insoluble polytetrafluoroethylene petri dish was charged with 15 g of latex, air-dried at 25 ° C. for 2 days, and then vacuum-dried at 40 ° C. for 24 hours, and precisely weighed 300 mg of a carboxyl group-containing synthetic polyisoprene. The group-containing synthetic polyisoprene was immersed in 100 ml of tetrahydrofuran in a 100 mesh stainless steel wire cage and allowed to stand at 25 ° C. for 48 hours. The soaked soot was pulled up from tetrahydrofuran, air-dried, and then vacuum-dried together with the soot at 60 ° C. overnight. After drying, the amount of insoluble matter remaining in the basket was precisely weighed and the proportion (%) of the weight of the carboxyl group-containing synthetic polyisoprene before being immersed in tetrahydrofuran was calculated to determine the amount of tetrahydrofuran insoluble matter.

Based on the tensile strength, elongation, and 500% tensile stress ASTM D412 of the dip-molded body, a film-shaped dip-molded body having a film thickness of about 0.2 mm is converted into a dumbbell (trade name “Super Dumbbell (Model: SDMK-100C)”. (Manufactured by Dumbbell Co., Ltd.), and a tensile strength measurement test piece was produced. The test piece is pulled with a Tensilon universal testing machine (trade name “RTG-1210”, manufactured by A & D) at a tensile speed of 500 mm / min, tensile strength immediately before break (unit: MPa), elongation just before break (unit:%) The tensile stress (unit: MPa) when the elongation was 500% was measured.

Based on tear strength ASTM D624-00 dip molded product, a film-like dip molded product having a film thickness of about 0.2 mm, 23 ° C., after standing for at least 24 hours at a relative humidity of 50% of the constant temperature and humidity chamber, A test piece for measuring the tear strength was produced by punching with a dumbbell (trade name “Die C”, manufactured by Dumbbell). The test piece was pulled with a Tensilon universal testing machine (trade name “RTG-1210”, manufactured by A & D) at a tensile speed of 500 mm / min, and the tear strength (unit: N / mm) was measured.

Tensile force immediately after a film-shaped dip-molded body having a stress retention rate of about 0.2 mm is made to have an elongation rate of 100% using a Tensilon universal testing machine (trade name “RTG-1210”, manufactured by Orientec Corp.) Measure stress and tensile stress after holding for 6 minutes at 100% elongation, and stress retention (tensile stress after holding for 6 minutes at 100% elongation / tensile stress immediately after 100% elongation) (Unit:%) was determined.

Test pieces obtained by cutting a film-shaped dip-molded body having a patch test film thickness of about 0.2 mm into a size of 10 × 10 mm were attached to the arms of 10 subjects. Thereafter, the presence of allergic symptoms of immediate type allergy (Type I) was confirmed by observing the applied part 180 minutes later, and further, 48 hours later, the applied part was observed to observe delayed type allergy (Type IV). The presence or absence of allergic symptoms was confirmed and evaluated according to the following criteria.
○: For all subjects, no allergic symptoms were observed at 180 minutes and 48 hours after application.
X: For all subjects, no allergic symptoms were observed 180 minutes after application, but for some subjects, allergic symptoms were observed 48 hours after application.

Production Example 1
100 parts of a synthetic polyisoprene having a weight average molecular weight of 1,300,000 (trade name “NIPOL IR2200L”, manufactured by Nippon Zeon Co., Ltd., isoprene homopolymer, cis bond unit amount 98%) is mixed with 1,150 parts of cyclohexane. While stirring, the temperature was raised to 60 ° C. to dissolve, and a cyclohexane solution (a) of synthetic polyisoprene was prepared.

  On the other hand, 10 parts of sodium rosinate and 5 parts of sodium dodecylbenzenesulfonate are mixed with water, and a mixture of sodium rosinate / sodium dodecylbenzenesulfonate = 2/1 in a weight ratio at a temperature of 60 ° C. An aqueous anionic surfactant solution (b) having a concentration of 1.5% by weight was prepared.

  Next, the cyclohexane solution (a) and the aqueous anionic surfactant solution (b) are adjusted to have a weight ratio of 1: 1.5 (at this time, the solid content ratio is polyisoprene: anionic). Surfactant = 8: 2.25), trade name “Multiline Mixer MS26-MMR-5.5L” (manufactured by Satake Chemical Machinery Co., Ltd.), followed by trade name “Milder MDN310” (Pacific (Established by Kiko Co., Ltd.) was mixed and emulsified at 4100 rpm to obtain an emulsion (c). At that time, the total feed flow rate of the cyclohexane solution (a) and the anionic surfactant aqueous solution (b) was 2,000 kg / hr, the temperature was 60 ° C., and the back pressure (gauge pressure) was 0.5 MPa.

  Next, the emulsion (c) is heated to 80 ° C. under a reduced pressure of −0.01 to −0.09 MPa (gauge pressure), cyclohexane is distilled off, and an aqueous dispersion (d) of synthetic polyisoprene is obtained. Obtained. At that time, the product name “SM5515” (manufactured by Dow Corning Toray) was used as an antifoaming agent, and was continuously sprayed so as to be 300 ppm by weight with respect to the synthetic polyisoprene in the emulsion (c). The addition was made. When distilling off cyclohexane, the emulsified liquid (c) is adjusted to 70% by volume or less of the tank volume, and a three-stage inclined paddle blade is used as a stirring blade, and the stirring is slowly performed at 60 rpm. Carried out.

  And after the distillation of cyclohexane was completed, the obtained aqueous dispersion (d) was 4,000 to 5,000 G using a continuous centrifuge (trade name “SRG510”, manufactured by Alfa Laval). Centrifugation was performed to obtain a synthetic polyisoprene latex (e1) having a solid concentration of 56% by weight as a light liquid. The conditions for the centrifugation are as follows: the solid concentration of the aqueous dispersion (d) before centrifugation is 10% by weight, the flow rate during continuous centrifugation is 1300 kg / hr, and the back pressure (gauge pressure) of the centrifuge is It was 1.5 MPa. The resulting synthetic polyisoprene latex (e1) has a solid content concentration of 56% by weight, a volume average particle size of 1.0 μm, pH = 10, a viscosity measured by a B-type viscometer of 120 mPa · s, an anionic surface activity. The total content of the agent was 3.0 parts per 100 parts of synthetic polyisoprene. Aggregates in the latex (e1) were not observed, and the amount of residual metals (total content of aluminum atoms and titanium atoms) in the latex (e1) was 250 ppm by weight.

Production Example 2
Instead of using synthetic polyisoprene (trade name “NIPOL IR2200L”, manufactured by Nippon Zeon Co., Ltd.), a styrene-isoprene-styrene block copolymer (SIS) (trade name “QUINTAC 3620” manufactured by Nippon Zeon Co., Ltd.) was used. A styrene-isoprene-styrene block copolymer latex (e2) was obtained in the same manner as in Production Example 1.

Example 1
Preparation of latex of carboxyl group-containing synthetic polyisoprene (A1-1) To 100 parts of synthetic polyisoprene of synthetic polyisoprene latex (e1) obtained in Production Example 1, 850 parts of distilled water was added and diluted. The diluted latex was charged into a nitrogen-substituted polymerization reactor equipped with a stirrer, and the temperature was raised to 30 ° C. while stirring. Moreover, 10 parts of methacrylic acid and 16 parts of distilled water were mixed using another container, and the methacrylic acid dilution liquid was prepared. This diluted methacrylic acid solution was added to the polymerization reaction vessel heated to 30 ° C. over 30 minutes.

  Furthermore, using another container, 7 parts of distilled water, 0.32 parts of sodium formaldehyde sulfoxylate (trade name “SFS”, manufactured by Mitsubishi Gas Chemical Company), ferrous sulfate (trade name “Frost Fe”, Chubu Kirestu) A solution (g) consisting of 0.01 part was prepared. After this solution (g) was added to the polymerization reaction vessel, 1 part of 1,1,3,3-tetramethylbutyl hydroperoxide (trade name “Perocta H”, manufactured by NOF Corporation) was added at 30 ° C. The mixture was reacted for 1 hour, and further reacted at 70 ° C. for 2 hours to carry out graft polymerization. The conversion rate of graft polymerization was 99% by weight. The introduction ratio of methacrylic acid monomer units (carboxyl group modification rate) was 3% by weight with respect to the total isoprene units.

  After the reaction, sodium hydroxide was added to adjust the pH to 10, and then this was centrifuged at 4,000 to 5,000 G using a continuous centrifuge (trade name “SRG510”, manufactured by Alfa Laval). (The flow rate is 1700 kg / hr, the back pressure (gauge pressure) of the centrifuge is 0.08 MPa), the solid content concentration is 56% by weight, the pH is 10, the viscosity measured with a B-type viscometer is 180 mPa · s, Volume average particle size is 1.0 μm, total content of anionic surfactant is 1.9 parts (based on 100 parts by weight of carboxyl group-containing synthetic polyisoprene), residual cyclohexane is 10 ppm by weight, 1,1,3 1,1,3,3-tetramethyl-1-butanol (boiling point: 145 ° C.), which is a decomposition product of 1,3-tetramethylbutyl hydroperoxide, has a residual amount of 119 ppm by weight. To obtain a latex of a group containing synthetic polyisoprene (A1-1). In addition, the tetrahydrofuran insoluble content of the carboxyl group-containing synthetic polyisoprene (A1-1) in the latex was 30% or more.

Preparation of Latex Composition First, a polymer was obtained by adding sodium hydroxide to a styrene-maleic acid mono-sec-butyl ester-maleic acid monomethyl ester polymer (trade name “Scripset 550”, manufactured by Hercules). The carboxyl group therein was neutralized 100% to prepare an aqueous sodium salt solution (concentration: 10% by weight) as the dispersant (i). And this dispersing agent (i) is made into 0.8 parts in conversion of solid content with respect to 100 parts of carboxyl group-containing synthetic polyisoprene (A1-1) obtained above, and carboxyl group-containing It was added to the latex of synthetic polyisoprene (A1-1). Then, while stirring the obtained mixture, each of the aqueous solution of sodium aluminate having a pH of 12 is 1 part in terms of solid content with respect to 100 parts of the carboxyl group-containing synthetic polyisoprene (A1-1) in the mixture. After adding the aqueous dispersion of the compounding agent, an aqueous potassium hydroxide solution was added to obtain a latex composition (j) adjusted to pH 10.5. Thereafter, the obtained latex composition (j) was aged (pre-crosslinked) for 48 hours in a thermostatic bath at 25 ° C.

A glass mold (diameter: about 5 cm, length of the crushed portion: about 15 cm) on which the production surface of the dip-molded body was ground was washed, preheated in an oven at 70 ° C., then 18 wt% calcium nitrate and 0.05 wt% It was immersed for 5 seconds in an aqueous solution of a coagulant made of polyoxyethylene lauryl ether (trade name “Emulgen 109P”, manufactured by Kao Corporation) and taken out. The glass mold coated with the coagulant was then dried in an oven at 70 ° C. Thereafter, the glass mold coated with the coagulant is taken out of the oven, dipped in the latex composition (j) obtained above at 25 ° C. for 10 seconds, taken out, and dried at room temperature for 60 minutes. Thus, a glass mold coated with a film was obtained. And after immersing the glass type | mold coat | covered with this film in 60 degreeC warm water for 2 minutes, it air-dried at room temperature for 30 minutes. Thereafter, the glass mold coated with this film was placed in an oven at 120 ° C. for crosslinking for 20 minutes. The glass mold covered with the crosslinked film was cooled to room temperature, talc was sprayed, and then the film was peeled from the glass mold to obtain a film (dip molded article) having a film thickness of about 0.2 mm. . And about the obtained film (dip molding), each measurement and evaluation of tensile strength, elongation, 500% tensile stress, tear strength, stress retention, and a patch test were performed. The results are shown in Table 1.

Example 2
When preparing the latex composition, the same procedure as in Example 1 was used except that the sodium aluminate aqueous solution added to the carboxyl group-containing synthetic polyisoprene (A1-1) was adjusted to pH 8. A latex composition and a dip-molded body having a pH of 10.5 were obtained and evaluated in the same manner. The results are shown in Table 1.

Example 3
By changing the amount of diluted methacrylic acid added to the synthetic polyisoprene latex (e1), the introduction ratio (carboxyl group modification rate) of methacrylic acid monomer units by graft polymerization is less than the total isoprene units. The latex of carboxyl group-containing polyisoprene (A1-2) was obtained in the same manner as in Example 1 except that the content was adjusted to 1 wt%.
And it replaced with the latex of carboxyl group-containing synthetic polyisoprene (A1-1), and carried out similarly to Example 1 except having used the latex of the carboxyl group-containing polyisoprene (A1-2) obtained above. A latex composition and a dip-molded body having a pH of 10.5 were obtained and evaluated in the same manner. The results are shown in Table 1.

Example 4
In preparing the latex composition, 0.4 parts of sulfur as a sulfur-based vulcanizing agent and zinc diethyldithiocarbamate (as a sulfur-based vulcanization accelerator) with respect to 100 parts of the carboxyl group-containing synthetic polyisoprene (A1-2). Example 3 except that a total of 0.25 parts of Ouchi Emerging Chemical Industries, Noxeller EZ) and zinc dibutyldithiocarbamate (Ouchi Emerging Chemical Industries, Noxeller BZ-P (BZ)) were added respectively. In the same manner as above, a latex composition and a dip-molded body having a pH of 10.5 were obtained and evaluated in the same manner. The results are shown in Table 1.

Example 5
0.8 parts of sulfur, a sulfur vulcanizing agent, zinc diethyldithiocarbamate (Noxeller EZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.) and zinc dibutyldithiocarbamate (Emerging Ouchi) Latex composition and dip having a pH of (10.5) in the same manner as in Example 4 except that the amount of NOCELLER BZ-P (BZ)) manufactured by Chemical Industries, Ltd. was changed to 0.5 parts in total. A molded product was obtained and evaluated in the same manner, and the results are shown in Table 1.

Example 6
In place of the synthetic polyisoprene latex (e1) obtained in Production Example 1, the styrene-isoprene-styrene block copolymer latex (e2) obtained in Production Example 2 was used, and the methacrylic acid diluted solution to be added The amount was changed so that the introduction ratio (carboxyl group modification rate) of the methacrylic acid monomer units by graft polymerization was 1% by weight with respect to the total isoprene units contained in the styrene-isoprene-styrene block copolymer. Except for the above, a latex of carboxyl group-containing SIS (A2-1) was obtained in the same manner as in Example 1.
Then, in place of the latex of carboxyl group-containing synthetic polyisoprene (A1-1), except that the latex of carboxyl group-containing SIS (A2-1) obtained above was used, in the same manner as in Example 5, A latex composition and a dip-molded body having a pH of 10.5 were obtained and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 1
Example except that the latex of the synthetic polyisoprene (A1′-3) obtained in Production Example 1 was used in place of the latex of the carboxyl group-containing synthetic polyisoprene (A1-1). In the same manner as in Example 1, a latex composition having a pH of 10.5 and a dip-molded article were obtained and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 2
Sodium aluminate aqueous solution was not added, and sulfur addition as a sulfur vulcanizing agent was 1.6 parts, and diethyldithiocarbamate zinc as a sulfur vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Industries, Noxeller) EZ) and zinc dibutyldithiocarbamate (manufactured by Ouchi Shinsei Kagaku Kogyo Co., Ltd., Noxeller BZ-P (BZ)) were changed to a total of 1.0 part in the same manner as in Example 4 except that the pH was A latex composition and a dip-molded body of 10.5 were obtained and evaluated in the same manner. The results are shown in Table 1.

From Table 1, a dip-molded product obtained using a latex composition obtained by adding an aqueous solution of an aluminum compound to a latex of carboxyl group-containing synthetic polyisoprene or carboxyl group-containing styrene-isoprene-styrene block copolymer is a patch Since the results of the test were good, it was possible to prevent the occurrence of allergic symptoms of delayed type allergy (Type IV) in addition to immediate allergy (Type I), and further, tensile strength, tensile elongation And excellent mechanical properties such as 500% tensile stress, tear strength and stress retention (Examples 1 to 6).
On the other hand, the dip-molded article obtained using the latex composition using the unmodified synthetic polyisoprene did not proceed with crosslinking with the aluminum compound, and could not obtain a dip-molded article that could be evaluated (comparison). Example 1).
In addition, when a considerable amount of a sulfur-based crosslinking agent and a sulfur-based crosslinking accelerator are used in place of the aluminum compound aqueous solution, the resulting dip-molded product is a delayed allergy (type IV) allergy as a result of a patch test. As a result, symptoms occurred (Comparative Example 2).

Claims (10)

  A latex composition obtained by adding an aqueous aluminum compound solution to latex of carboxyl group-containing synthetic polyisoprene and / or carboxyl group-containing styrene-isoprene-styrene block copolymer.   The latex composition according to claim 1, wherein the aqueous aluminum compound solution has a pH of 5 to 13.   The latex composition according to claim 1 or 2, wherein the aluminum compound aqueous solution is an aqueous solution of a metal salt of aluminate.   The latex composition according to any one of claims 1 to 3, wherein the carboxyl group-containing synthetic polyisoprene is obtained by graft polymerization of a monomer having a carboxyl group to the synthetic polyisoprene.   The carboxyl group-containing styrene-isoprene-styrene block copolymer is obtained by graft polymerization of a monomer having a carboxyl group to a styrene-isoprene-styrene block copolymer. A latex composition according to claim 1.   The present invention further comprises 0.05 to 1.0 part by weight of a sulfur vulcanizing agent based on 100 parts by weight of the total of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing styrene-isoprene-styrene block copolymer. Item 6. The latex composition according to any one of Items 1 to 5.   0.05 to 1.0 part by weight of a sulfur-based vulcanization accelerator is further contained with respect to 100 parts by weight in total of the carboxyl group-containing synthetic polyisoprene and the carboxyl group-containing styrene-isoprene-styrene block copolymer. The latex composition according to any one of claims 1 to 6.   The latex composition according to any one of claims 1 to 7, which has a pH of 7 to 13.   The film molded object which consists of a latex composition in any one of Claims 1-8.   A method for producing a dip-molded article, comprising a step of dip-molding the latex composition according to claim 1.